Pusa Campus, ICAR-Indian Institute of Maize Research, New Delhi, India.
Pusa Campus, ICAR-Indian Agricultural Research Institute, New Delhi, Delhi, India.
PeerJ. 2024 Mar 27;12:e17190. doi: 10.7717/peerj.17190. eCollection 2024.
Maize production and productivity are affected by drought stress in tropical and subtropical ecologies, as the majority of the area under maize cultivation in these ecologies is rain-fed. The present investigation was conducted to study the physiological and biochemical effects of 24-Epibrassinolide (EBR) as a plant hormone on drought tolerance in maize. Two maize hybrids, Vivek hybrid 9 and Bio 9637, were grown under three different conditions: (i) irrigated, (ii) drought, and (iii) drought+EBR. A total of 2 weeks before the anthesis, irrigation was discontinued to produce a drought-like condition. In the drought+EBR treatment group, irrigation was also stopped, and in addition, EBR was applied as a foliar spray on the same day in the drought plots. It was observed that drought had a major influence on the photosynthesis rate, membrane stability index, leaf area index, relative water content, and leaf water potential; this effect was more pronounced in Bio 9637. Conversely, the activities of antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), and superoxide dismutase (SOD) increased in both hybrids under drought conditions. Specifically, Vivek hybrid 9 showed 74% higher CAT activity under drought conditions as compared to the control. Additionally, EBR application further enhanced the activity of this enzyme by 23% compared to plants under drought conditions. Both hybrids experienced a significant reduction in plant girth due to drought stress. However, it was found that exogenously applying EBR reduced the detrimental effects of drought stress on the plant, and this effect was more pronounced in Bio 9637. In fact, Bio 9637 treated with EBR showed an 86% increase in proline content and a 70% increase in glycine betaine content compared to untreated plants under drought conditions. Taken together, our results suggested EBR enhanced tolerance to drought in maize hybrids. Hence, pre-anthesis foliar application of EBR might partly overcome the adverse effects of flowering stage drought in maize.
玉米的生产和生产力受到热带和亚热带生态系统中干旱胁迫的影响，因为这些生态系统中大部分玉米种植区都是雨养的。本研究旨在研究 24-表油菜素内酯（EBR）作为一种植物激素对玉米耐旱性的生理和生化影响。选用两个玉米杂交种，Vivek 杂交 9 号和 Bio 9637，在三种不同条件下进行种植：（i）灌溉、（ii）干旱和（iii）干旱+EBR。在开花前 2 周，停止灌溉以产生类似干旱的条件。在干旱+EBR 处理组中，也停止了灌溉，此外，在干旱地块当天还进行了叶面喷施 EBR。结果表明，干旱对光合作用速率、膜稳定性指数、叶面积指数、相对水含量和叶片水势有重大影响；这种影响在 Bio 9637 中更为明显。相反，在干旱条件下，两种杂交种的抗氧化酶如过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）和超氧化物歧化酶（SOD）的活性增加。具体来说，与对照相比，干旱条件下 Vivek 杂交 9 的 CAT 活性增加了 74%。此外，与干旱条件下的植物相比，EBR 的应用使该酶的活性进一步提高了 23%。由于干旱胁迫，两种杂交种的植物周长都显著减少。然而，研究发现，外源施用 EBR 可以减轻干旱胁迫对植物的不利影响，在 Bio 9637 中更为明显。事实上，与干旱条件下未处理的植物相比，Bio 9637 用 EBR 处理后脯氨酸含量增加了 86%，甘氨酸甜菜碱含量增加了 70%。综上所述，EBR 增强了玉米杂交种对干旱的耐受性。因此，开花前叶面喷施 EBR 可能部分克服了玉米花期干旱的不利影响。
